<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <button>请求</button>
    <script>
        document.querySelector("button").onclick =function(){
            var xhr = new XMLHttpRequest();
            xhr.open('get','http://localhost:3000/users');
            xhr.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded')

        }
    </script>
</body>
</html>